/* ----------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date:        19. March 2015
* $Revision: 	V.1.4.5
*
* Project: 	    CMSIS DSP Library
* Title:	    arm_lms_q15.c
*
* Description:	Processing function for the Q15 LMS filter.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in
*     the documentation and/or other materials provided with the
*     distribution.
*   - Neither the name of ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* -------------------------------------------------------------------- */

#include "arm_math.h"
/**
 * @ingroup groupFilters
 */

/**
 * @addtogroup LMS
 * @{
 */

/**
* @brief Processing function for Q15 LMS filter.
* @param[in] *S points to an instance of the Q15 LMS filter structure.
* @param[in] *pSrc points to the block of input data.
* @param[in] *pRef points to the block of reference data.
* @param[out] *pOut points to the block of output data.
* @param[out] *pErr points to the block of error data.
* @param[in] blockSize number of samples to process.
* @return none.
*
* \par Scaling and Overflow Behavior:
* The function is implemented using a 64-bit internal accumulator.
* Both coefficients and state variables are represented in 1.15 format and multiplications yield a 2.30 result.
* The 2.30 intermediate results are accumulated in a 64-bit accumulator in 34.30 format.
* There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved.
* After all additions have been performed, the accumulator is truncated to 34.15 format by discarding low 15 bits.
* Lastly, the accumulator is saturated to yield a result in 1.15 format.
*
* \par
* 	In this filter, filter coefficients are updated for each sample and the updation of filter cofficients are saturted.
*
*/

void arm_lms_q15(
    const arm_lms_instance_q15 *S,
    q15_t *pSrc,
    q15_t *pRef,
    q15_t *pOut,
    q15_t *pErr,
    uint32_t blockSize)
{
    q15_t *pState = S->pState;                     /* State pointer */
    uint32_t numTaps = S->numTaps;                 /* Number of filter coefficients in the filter */
    q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer */
    q15_t *pStateCurnt;                            /* Points to the current sample of the state */
    q15_t mu = S->mu;                              /* Adaptive factor */
    q15_t *px;                                     /* Temporary pointer for state */
    q15_t *pb;                                     /* Temporary pointer for coefficient buffer */
    uint32_t tapCnt, blkCnt;                       /* Loop counters */
    q63_t acc;                                     /* Accumulator */
    q15_t e = 0;                                   /* error of data sample */
    q15_t alpha;                                   /* Intermediate constant for taps update */
    q31_t coef;                                    /* Teporary variable for coefficient */
    q31_t acc_l, acc_h;
    int32_t lShift = (15 - (int32_t) S->postShift);       /*  Post shift  */
    int32_t uShift = (32 - lShift);


#ifndef ARM_MATH_CM0_FAMILY

    /* Run the below code for Cortex-M4 and Cortex-M3 */


    /* S->pState points to buffer which contains previous frame (numTaps - 1) samples */
    /* pStateCurnt points to the location where the new input data should be written */
    pStateCurnt = &(S->pState[(numTaps - 1u)]);

    /* Initializing blkCnt with blockSize */
    blkCnt = blockSize;

    while(blkCnt > 0u)
    {
        /* Copy the new input sample into the state buffer */
        *pStateCurnt++ = *pSrc++;

        /* Initialize state pointer */
        px = pState;

        /* Initialize coefficient pointer */
        pb = pCoeffs;

        /* Set the accumulator to zero */
        acc = 0;

        /* Loop unrolling.  Process 4 taps at a time. */
        tapCnt = numTaps >> 2u;

        while(tapCnt > 0u)
        {
            /* acc +=  b[N] * x[n-N] + b[N-1] * x[n-N-1] */
            /* Perform the multiply-accumulate */
#ifndef UNALIGNED_SUPPORT_DISABLE

            acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);
            acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);

#else

            acc += (q63_t) (((q31_t) (*px++) * (*pb++)));
            acc += (q63_t) (((q31_t) (*px++) * (*pb++)));
            acc += (q63_t) (((q31_t) (*px++) * (*pb++)));
            acc += (q63_t) (((q31_t) (*px++) * (*pb++)));


#endif	/*	#ifndef UNALIGNED_SUPPORT_DISABLE	*/

            /* Decrement the loop counter */
            tapCnt--;
        }

        /* If the filter length is not a multiple of 4, compute the remaining filter taps */
        tapCnt = numTaps % 0x4u;

        while(tapCnt > 0u)
        {
            /* Perform the multiply-accumulate */
            acc += (q63_t) (((q31_t) (*px++) * (*pb++)));

            /* Decrement the loop counter */
            tapCnt--;
        }

        /* Calc lower part of acc */
        acc_l = acc & 0xffffffff;

        /* Calc upper part of acc */
        acc_h = (acc >> 32) & 0xffffffff;

        /* Apply shift for lower part of acc and upper part of acc */
        acc = (uint32_t) acc_l >> lShift | acc_h << uShift;

        /* Converting the result to 1.15 format and saturate the output */
        acc = __SSAT(acc, 16);

        /* Store the result from accumulator into the destination buffer. */
        *pOut++ = (q15_t) acc;

        /* Compute and store error */
        e = *pRef++ - (q15_t) acc;

        *pErr++ = (q15_t) e;

        /* Compute alpha i.e. intermediate constant for taps update */
        alpha = (q15_t) (((q31_t) e * (mu)) >> 15);

        /* Initialize state pointer */
        /* Advance state pointer by 1 for the next sample */
        px = pState++;

        /* Initialize coefficient pointer */
        pb = pCoeffs;

        /* Loop unrolling.  Process 4 taps at a time. */
        tapCnt = numTaps >> 2u;

        /* Update filter coefficients */
        while(tapCnt > 0u)
        {
            coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
            *pb++ = (q15_t) __SSAT((coef), 16);
            coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
            *pb++ = (q15_t) __SSAT((coef), 16);
            coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
            *pb++ = (q15_t) __SSAT((coef), 16);
            coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
            *pb++ = (q15_t) __SSAT((coef), 16);

            /* Decrement the loop counter */
            tapCnt--;
        }

        /* If the filter length is not a multiple of 4, compute the remaining filter taps */
        tapCnt = numTaps % 0x4u;

        while(tapCnt > 0u)
        {
            /* Perform the multiply-accumulate */
            coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
            *pb++ = (q15_t) __SSAT((coef), 16);

            /* Decrement the loop counter */
            tapCnt--;
        }

        /* Decrement the loop counter */
        blkCnt--;

    }

    /* Processing is complete. Now copy the last numTaps - 1 samples to the
       satrt of the state buffer. This prepares the state buffer for the
       next function call. */

    /* Points to the start of the pState buffer */
    pStateCurnt = S->pState;

    /* Calculation of count for copying integer writes */
    tapCnt = (numTaps - 1u) >> 2;

    while(tapCnt > 0u)
    {

#ifndef UNALIGNED_SUPPORT_DISABLE

        *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
        *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
#else
        *pStateCurnt++ = *pState++;
        *pStateCurnt++ = *pState++;
        *pStateCurnt++ = *pState++;
        *pStateCurnt++ = *pState++;
#endif

        tapCnt--;

    }

    /* Calculation of count for remaining q15_t data */
    tapCnt = (numTaps - 1u) % 0x4u;

    /* copy data */
    while(tapCnt > 0u)
    {
        *pStateCurnt++ = *pState++;

        /* Decrement the loop counter */
        tapCnt--;
    }

#else

    /* Run the below code for Cortex-M0 */

    /* S->pState points to buffer which contains previous frame (numTaps - 1) samples */
    /* pStateCurnt points to the location where the new input data should be written */
    pStateCurnt = &(S->pState[(numTaps - 1u)]);

    /* Loop over blockSize number of values */
    blkCnt = blockSize;

    while(blkCnt > 0u)
    {
        /* Copy the new input sample into the state buffer */
        *pStateCurnt++ = *pSrc++;

        /* Initialize pState pointer */
        px = pState;

        /* Initialize pCoeffs pointer */
        pb = pCoeffs;

        /* Set the accumulator to zero */
        acc = 0;

        /* Loop over numTaps number of values */
        tapCnt = numTaps;

        while(tapCnt > 0u)
        {
            /* Perform the multiply-accumulate */
            acc += (q63_t) ((q31_t) (*px++) * (*pb++));

            /* Decrement the loop counter */
            tapCnt--;
        }

        /* Calc lower part of acc */
        acc_l = acc & 0xffffffff;

        /* Calc upper part of acc */
        acc_h = (acc >> 32) & 0xffffffff;

        /* Apply shift for lower part of acc and upper part of acc */
        acc = (uint32_t) acc_l >> lShift | acc_h << uShift;

        /* Converting the result to 1.15 format and saturate the output */
        acc = __SSAT(acc, 16);

        /* Store the result from accumulator into the destination buffer. */
        *pOut++ = (q15_t) acc;

        /* Compute and store error */
        e = *pRef++ - (q15_t) acc;

        *pErr++ = (q15_t) e;

        /* Compute alpha i.e. intermediate constant for taps update */
        alpha = (q15_t) (((q31_t) e * (mu)) >> 15);

        /* Initialize pState pointer */
        /* Advance state pointer by 1 for the next sample */
        px = pState++;

        /* Initialize pCoeffs pointer */
        pb = pCoeffs;

        /* Loop over numTaps number of values */
        tapCnt = numTaps;

        while(tapCnt > 0u)
        {
            /* Perform the multiply-accumulate */
            coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
            *pb++ = (q15_t) __SSAT((coef), 16);

            /* Decrement the loop counter */
            tapCnt--;
        }

        /* Decrement the loop counter */
        blkCnt--;

    }

    /* Processing is complete. Now copy the last numTaps - 1 samples to the
       start of the state buffer. This prepares the state buffer for the
       next function call. */

    /* Points to the start of the pState buffer */
    pStateCurnt = S->pState;

    /*  Copy (numTaps - 1u) samples  */
    tapCnt = (numTaps - 1u);

    /* Copy the data */
    while(tapCnt > 0u)
    {
        *pStateCurnt++ = *pState++;

        /* Decrement the loop counter */
        tapCnt--;
    }

#endif /*   #ifndef ARM_MATH_CM0_FAMILY */

}

/**
   * @} end of LMS group
   */
